Produção de doce de leite com proteína do soro microparticulada: um estudo sobre mudanças físico-químicas e reológicas

Abstract

Doce de leite is a dairy product originated in Latin American countries, with Brazil being one of the main producers and consumers. This product is widely used for direct consumption or in industrial applications, and thickening agents can be used as an alternative to modify its rheological properties. The growing demand for foods with greater nutritional value has encouraged the industry to incorporate different types of proteins into the formulation of various products. Microparticulate proteins, already used in the composition of some foods, stand out for their high thermal stability compared to native proteins, as well as acting as fat substitutes and helping to modify the organoleptic characteristics of the product, while simultaneously contributing to increasing its nutritional value. The aim of this study was to evaluate the impact of partially replacing milk with concentrated whey protein (WPC) and microparticulated whey protein (MWP) in the manufacture of doce de leite, at concentrations of 2.1% and 4.2% (w.w-¹), comparing its physicochemical and rheological properties with the traditional product, in which the same proportion of substitution was made with skimmed milk powder (SMP). To this end, the microparticulated whey proteins were produced and characterized, as well as the doces de leite formulated. Analyses of particle size and the additional denaturation generated by the microparticulation process were carried out on the protein solutions before and after processing. In addition, physicochemical and centesimal composition analyses were carried out, as well as an assessment of the mineral composition of the ash by energy dispersive spectroscopy (EDS), quantification of Maillard reaction indicators (HMF by HPLC-PDA), colorimetry (CIELab), browning index, texture (TPA) and rheology. The microparticulation process resulted in a reduction in the average particle size, from 10.62 µm to 4.88 µm, and additional denaturation of the α-lactalbumin and β-lactoglobulin proteins, with rates of 62.3% and 96.5%, respectively. The composition of the doces de leite is in line with Mercosur regulations, except for the fat content, where the result was slightly lower. The concentration of HMF increased until the 15th day of storage, declining thereafter. The control product (SMP) showed higher browning index and color saturation values than the products with WPC and MWP at both substitution concentrations. In addition, the formulations containing WPC and especially MWP showed significant increases in hardness, gumminess and apparent viscosity compared to traditional doce de leite, with the 4.2%MWP formulation showing the highest values. It is concluded that the addition of MWP represents a viable alternative for modulating the rheological and textural characteristics of doce de leite without significantly altering its centesimal composition, offering an alternative to the use of thickeners in this type of product.